Usually its a long night so a comfortable mattress is very important, especially as you get older.  Thermarest have proven to be outstanding and recently I purchased a NeoAir XTerm, which exceeded even my high expectations.  It folds up smaller and lighter than my usual ProLite Plus as it has no foam inside, but it seems to retain head at least as well if not better.  Best of all its just that much thicker to provide a bit more cushioning for the old bones of mine.  Highly recommended.

BTW I got mine at a very good price from Fruugo so shop around.